Lockdowns, whilst necessary, were presumably bad for our brains on several fronts:

- they reduced social stimulation

- they increased repetitive behaviour

- layoffs and furloughs led to isolation

In addition there was a lot of screen time across all demographics. My uninformed opinion is that the repetitive and confirmatory nature of digital entertainment makes it a kind of cognitive "junk food"

There's also "anecdata" about COVID kids and even pets that have had challenges catching up with a post-lockdown world. I don't know how clear the evidence is, though.